Warm downstairs cold upstairs, anyone any ideas?

Well if you have extended the vent pipe under the water level unless the header tank is emptying it sounds like its pulling air in through the auto air bleeds, try shutting them, bleeding the system and running it again then report back.

ps if you paid a firm £1700 to fix the problem why havent they fixed it?
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the 1700 was for the powerflush, thermostatic valves on 13 rads, new ball valve, a new pump, 2 automatic bleed valves and the dreaded VAT. When he left he said that all rads were working and that he could either stay for another few hours to get them all bled or call him back in 3 - 4 days if the system still needed attention. I called him back and he fitted the automatic bleed valves to the down pipes to the kitchen. He advised that the next step was a new boiler and any further money thrown at the problem would be wasted if I went ahead and changed the system. I know the system is 20 years old but it was working perfectly until a few months ago so I cant see why it cant be restored back to at least 80% performance after the work which has been done. Not sure that the automatic bleed valves would be part of the equation as the rads were draining out before and after these were replaced but I will add it to the list of things to try.

Having stood over the system this morning and felt the pipes as they were heating up, the vent was the first to get the hottest which would account for hot water going into the header tank and overflowing outside. Although everything got hot eventually I am convinced that there must be sludge in the aerjec. I am assuming that there must also be a blockage somewhere in the cold water feed from the header tank and it is not replenishing the system, although it does when the system is switched off and the rads bled as you can hear the water refilling the tank. I think the test restraining the ball valve and draining the system slightly to see if the level in the tank goes down, along with the magnet test might confirm this.

Still dont fully understand how many problems I have got as I dont know where the air is coming from to replace the water in the radiators and I think my brain is now suffering from the same problem!
May take me a while to get these things checked but thanks to everyone and if anyone has any further ideas please let me know.
it all seems to revolve around the new pump and pumping over.
the pumping over into the header clearly is wrong and not cured by a dip loop, this is causing air in the system by constantly reoxygenating the water.

air allways migrates up hence the upstairs being cold.

not a cure but have you tried turning the pump speed down?

the open vent is after the pump thats why its pumping over rather than sucking air.

try opening every single trv, and the lock shields, why? because there is something wrong with the system resistances, its seeing less resistance to the open vent than the system, either its a blockage or not correctly balanced.
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they need to come back and deal with it. surely if you payed mor than bg prices they'll be giving some sort of guaruntee?
Any chance of a rough diagram to show how the F/E tank is connected into the system? There must be something dodgy about the layout.

My Vaillant was installed as shown below and works perfectly.
Hi, thanks for all your input overnight to answer what I know here goes:

I turned the pump down on advice from the diynot site and it seemed to improve the circulation for a while ie the rads upstairs started to get warm and hold their water. Then we had a disaster in the spare room with a washbasin tap fracturing. As it was late at night and we couldnt get access to the loft very easily so we turned all the taps on in the house so that the tank could not fill as quick as it would empty in order to make the repair, which was a success. Since then despite the pump being on lowest the air is back in the radiators. Wil try the lockshields first before the magnet test.

To Gavinda
I picked him out of yellow pages as an emergency plumber, he has been 4 times, I really didnt think that the prices were extortionate, I gave him the symptoms and he has recommended the work needing to be carried out and provided a price which I perceived to be reasonable for the work. I havent just given him an open cheque book and said solve it and as far as I can see there has been more than one thing wrong. What I cant and wont do now is give up and put a new system in until someone can identify exactly what the problem is and how much it would be to put it right and how long it would last. From what I can see from the posts, this is not a precise science and every engineer has had a different experience, which is why I would tap the knowledge base of this site before embarking on the solution to my problem.

To Jackthom
I will draw a diagram for you but how can it suddenly become dodgy when it has worked so well for the last 20 years. No pipework has been altered.
sorry nixter but the prices he;'s charged seem ridiculous. especially when hes not sorted it yet. how long did he flush the system for? .
Thought this ought to be a separate post,
Just when you thought you might be onto something..............

Woke up this morning to power cut.

Re-set the trip switch, turned on the boiler and you've guessed it, off went the power again. So now back to square one with no heat and no water.

The boiler fires up for about 15 secs so cant be a welded wire as assume the trip wouldnt let me switch any electrics back on would it?

Have now switched boiler off at the power socket and gone off to buy fuel for the woodburner which unfortunately does not have a backburner, nor do we have an immersion heater!
it sounds like you need to cut your losses with the last guy. call bg and go for a fixed rate repair. but be ready for us to advise o a poweerflush. mind you, it'll be done properly. you may just get away with having the cold feed and open vent cutting out and being repiped, but from the sounds of the prices you've paid and progress made, i suspect that sadly youve been ripped by the 'emergency plumber' :cry:

also ask freind family and neighbors for a recommendation as a lot of the good guys (private engineers) dont need to advertise much due to good old word of mouth.
Gavinda it took 2 people all day to power flush, replace all TRVS fit new pump. 9.30am to 6pm I think. I have since asked him to confirm that the power flush included not just the rads but the boiler and 'arterial' pipe work and he confirmed it did. TRVS were £35 plus VAT x 13 off. No one had ever told me that you should power flush every 5 years, I have only had the boiler serviced before.
Ok for one DO NOT CONVERT THE SYSTEM TO A SEALED SYTEM (WITH EXPANSION VESSEL) BEFORE CHECKING THAT THE BOILER IS SUITABLE TO BE INSTALLED ON A SEALED SYATEM. Not all boilers are designed to withstand upto 3 bar pressure. If your boiler is not suitable then the main heat exchanger may crack andf begin to leak. ALSO THE BOILER HAS TO HAVE AN OVERHEAT THERMOSTAT FITTED TO STOP THE BOILER OPERATING IN OVERHEAT CONDITIONS. If not the boiler can be deemed as Immeadiately dangerous and could pose a threat to life and or property!!!! Also the sealed system has to have 5 main components. 1 overheat cutoff 2 pressure relief pipe 3 expansion vessel 4 pressure gauge 5 filling section (top up bottle or fillling loop )

Firstly I powerflush for the largest company ( no names but i think you can guess who ;) )

I can bet £1 million that the cold feed has not been cut out and cleared. Pumping over usually occurs in a central heating system due to a restricted "h" section. The "h" is where the open vent, cold feed and pump are. usually in the airing cupboard. Ensure this has been designed correctly. The flow pipe should come up from the boiler, then the open vent, then no more than 150mm the cold feed should join then the pump. The open vent needs to be ran in 22mm pipe, the cold feed in 15mm. the open vent pipe should rise above the header tank by at least 450mm. If the boiler has an overheat cut off then the open vent and cold feed can be combined into 1 22mm pipe.
Sorry forgot to mention a central heating system DOES NOT REQUIRE A POWERFLUSH EVERY 5 YEARS!!!! Sounds like someone is trying to retain customers. If in hard water arrears (all water will benefit) add inhibitor every 3 years. The system will need to be completely drained.

Also best way to clear air locks is to play with the pump speed setting, holding the lever between speeds will stop the pump allowing the air to escape up the open vent. ENSURE THE BOILER IS SWITCHED OFF TO PREVENT OVERHEATING. ( dont turn the whole system off via programmer / stats as this will also stop the pump, just the boiler stat/switch)
I would be cutting the airjec out and H the pipes . These are a bloody nuisance for blocking up and a power flush does not clean them properly . Also when an air sep gets bad the pipe all the way to the pump and sometimes to the motorised valves get choca and wont clean out properly
Ok for one DO NOT CONVERT THE SYSTEM TO A SEALED SYTEM (WITH EXPANSION VESSEL) BEFORE CHECKING THAT THE BOILER IS SUITABLE TO BE INSTALLED ON A SEALED SYATEM. Not all boilers are designed to withstand upto 3 bar pressure. If your boiler is not suitable then the main heat exchanger may crack andf begin to leak. ALSO THE BOILER HAS TO HAVE AN OVERHEAT THERMOSTAT FITTED TO STOP THE BOILER OPERATING IN OVERHEAT CONDITIONS. If not the boiler can be deemed as Immeadiately dangerous

somehow i fail to see how something that may or may not go wrong would be classed as id.

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